As city populations grow ever larger – and move from ‘mega’ to ‘giga’ status – what fresh sustainability challenges will they meet? In an article from our latest Unearthed Report for the Civil and Environmental industries, Seequent’s Head of Sustainability, Thomas Krom, highlights just a few.

“If you look at the number of people who are going to be living in cities in a reasonably short period of time, the figures are astronomical. Everybody is moving into town and there are a lot more of us. In fact, there are already more people living in cities today than were living on the planet when I was born… and I’m not even that old.”

By 2030 there are expected to be more than 40 megacities around the world – those with more than 10 million inhabitants. In 2014 the number stood at 28. The UN forecasts that by 2050, 68% of the world’s population will be living in cities. 2007 was the milestone year when city population outdistanced rural population for the first time.

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As population densities rise, cities face a plethora of challenges. Initially, it might seem efficient to congregate a large number of residents in one place. But the assumed sustainability of proximity is quickly cancelled out by resource strain, and then there’s the additional heat that high-rise, air-conditioned buildings generate, stressing the microclimate.

One of the main challenge’s cities are facing is water stress. The increase in population densities and demand on water create an increased risk of water shortages. According to the United Nations recent report on World Water Development, at present, there are an estimated 3.6 billion people (nearly half the global population) living in areas that are potentially water-scarce at least one month per year, and this population could increase to some 4.8 to 5.7 billion by 2050.

There is much debate over the cause of these challenges, but the fact is that temperatures are rising and clearly sea levels are rising too. You can sit there with a ruler and measure it. Jakarta is sinking by as much as 15cm per year, a problem that has been exacerbated by the extraction of groundwater to support an inadequate piped water supply.

So, are there solutions? In continental Europe, where district central heating is widespread, some authorities cool the return water by running it through the sidewalks during the winter. This keeps the sidewalks warm, so there’s less need to combat ice with salt, and all its environmental drawbacks. It also means the return water is colder when it reaches the district central heating plant, which is better for the plant and the process.

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Also, the UN’s World Water Development report reviewed nature-based solutions to solving some of these challenges. The report looked at urban green infrastructure, including green buildings. This emerging phenomenon is establishing new benchmarks and technical standards that embrace nature-based solutions and become sustainable ways of improving the environmental challenges of these large conurbations.

But clever as they are, these are just small ideas. We only have so much money and time and so much grey matter resource, and we need to focus that where we have the most bang for the bucks. There are some areas where you can see wider action being taken successfully, and one of those is rainwater management, observes Thomas, “largely because it’s an obvious financial winner, it’s easier to implement and it delivers immediate gains. Many of those advances are around being better at separating rainwater from sewage and then trying to get the rainwater into the ground as close to where it fell as possible.”

“It’s also one of the areas where Leapfrog can help. If you’re trying to infiltrate water into the city, there will be lots of hard surfaces you need to avoid, and you’ll want to do that in some engineered fashion that understands not all the soil underneath is equally permeable.
Everything will become much more interdependent and complex, which is where Leapfrog Works can contribute. It can give you a better understanding of the entire system below the surface to help these projects happen more efficiently. But it can also help to improve communication, addressing concerns about interference by creating models from our software so people can understand this interaction. The subsurface is only going to become more important in the cities of the future, so that understanding and communication is only going to become even more important.”

To read all the full articles, download your free copy of our Unearthed Report.

Volume three of our Unearthed Report covers topics from sustainability, living and working underground, to where our waste, cars and utilities are going.

If you have feedback, questions or any thoughts on what you’d like us to cover in future editions, please contact: [email protected]

For ongoing, industry relevant content, follow our Seequent Civil and Environmental page on LinkedIn.

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Dr Thomas Krom, Head of Sustainability, Seequent

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